U.S. patent application number 10/072972 was filed with the patent office on 2002-12-12 for supporting disk for a surface grinding wheel and surface grinding wheel.
This patent application is currently assigned to August Ruggeberg GmbH & Co.. Invention is credited to Gross, Gisela, Preissler, Bernd, Stuckenholz, Bernd, Trompelt, Bernd.
Application Number | 20020187737 10/072972 |
Document ID | / |
Family ID | 7673875 |
Filed Date | 2002-12-12 |
United States Patent
Application |
20020187737 |
Kind Code |
A1 |
Stuckenholz, Bernd ; et
al. |
December 12, 2002 |
Supporting disk for a surface grinding wheel and surface grinding
wheel
Abstract
A supporting disk for a surface grinding wheel comprises a
glass-fiber reinforced phenolic resin body which has an upper
covering layer of a textile glass fabric or a glass-yarn layer, an
intermediate layer of a fiber mat, and a lower covering layer of a
textile glass fabric or a glass-yarn layer.
Inventors: |
Stuckenholz, Bernd; (Wiehl,
DE) ; Trompelt, Bernd; (Crimmitschau, DE) ;
Preissler, Bernd; (Oschatz, DE) ; Gross, Gisela;
(Oschatz, DE) |
Correspondence
Address: |
BROWDY AND NEIMARK, P.L.L.C.
624 NINTH STREET, NW
SUITE 300
WASHINGTON
DC
20001-5303
US
|
Assignee: |
August Ruggeberg GmbH &
Co.
Marienheide
DE
|
Family ID: |
7673875 |
Appl. No.: |
10/072972 |
Filed: |
February 12, 2002 |
Current U.S.
Class: |
451/533 ;
451/544 |
Current CPC
Class: |
B24D 13/16 20130101;
B24D 9/08 20130101 |
Class at
Publication: |
451/533 ;
451/544 |
International
Class: |
B24B 007/16 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 12, 2001 |
DE |
101 06 631.7 |
Claims
What is claimed is:
1. A supporting disk for a surface grinding wheel, comprising a
glass-fiber reinforced phenolic resin body, which includes one of
an upper covering layer (6) of a textile glass fabric (9) and a
glass-yarn layer (10); an intermediate layer (7) of a fiber mat
(14); and one of a lower covering layer (8) of a textile glass
fabric (9) and a glass-yarn layer (10).
2. A supporting disk according to claim 1, wherein the intermediate
layer (7) is a fiber fleece.
3. A supporting disk according to claim 1, wherein the intermediate
layer (7) is a fabric of a volume enlarged by needling.
4. A supporting disk according to claim 1, wherein the intermediate
layer (7) is comprised of natural fibers.
5. A supporting disk according to claim 1, wherein the intermediate
layer (7) is comprised of synthetic organic fibers.
6. A supporting disk according to claim 1, wherein the intermediate
layer (7) is comprised of textile glass fibers.
7. A supporting disk according to claim 1, wherein the upper
covering layer (6), the intermediate layer (7) and the lower
covering layer (8) are sewn together.
8. A supporting disk according to claim 1, wherein the textile
glass fabric (9) and the glass-yarn layer (10) are comprised of
warp threads (11) and weft threads (12) which are glass-fiber
rovings.
9. A supporting disk according to claim 1, wherein the intermediate
layer (7) is thicker than the upper covering layer (6) and the
lower covering layer (8).
10. A supporting disk according to claim 1, wherein the upper
covering layer (6) and the lower covering layer (8) have a higher
tensile strength than the intermediate layer (7).
11. A surface grinding wheel comprising a supporting disk (1) and
abrasive laminas (2) fixed to the supporting disk (1), the
supporting disk (1) comprising a glass-fiber reinforced phenolic
resin body, which includes one of an upper covering layer (6) of a
textile glass fabric (9) and a glass-yarn layer (10); an
intermediate layer (7) of a fiber mat (14); and one of a lower
covering layer (8) of a textile glass fabric (9) and a glass-yarn
layer (10).
12. A surface grinding wheel according to claim 11, wherein the
intermediate layer (7) is a fiber fleece.
13. A surface grinding wheel according to claim 11, wherein the
intermediate layer (7) is a fabric of a volume enlarged by
needling.
14. A surface grinding wheel according to claim 11, wherein the
intermediate layer (7) is comprised of natural fibers.
15. A surface grinding wheel according to claim 11, wherein the
intermediate layer (7) is comprised of synthetic organic
fibers.
16. A surface grinding wheel according to claim 11, wherein the
intermediate layer (7) is comprised of textile glass fibers.
17. A surface grinding wheel according to claim 11, wherein the
upper covering layer (6), the intermediate layer (7) and the lower
covering layer (8) are sewn together.
18. A surface grinding wheel according to claim 11, wherein the
textile glass fabric (9) and the glass-yarn layer (10) are
comprised of warp threads (11) and weft threads (12) which are
glass-fiber rovings.
19. A surface grinding wheel according to claim 11, wherein the
intermediate layer (7) is thicker than the upper covering layer (6)
and the lower covering layer (8).
20. A surface grinding wheel according to claim 11, wherein the
upper covering layer (6) and the lower covering layer (8) have a
higher tensile strength than the intermediate layer (7).
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The invention relates to supporting disks for a surface
grinding wheel and to a surface grinding wheel comprising a
supporting disk.
[0003] 2. Background Art
[0004] Surface grinding wheels comprise a supporting disk and
abrasive laminas mounted thereon. The abrasive laminas, which
deliver stock removal upon operation, customarily comprise
commercial abrasives on a cotton or polyester substrate. As a rule,
the abrasive laminas are being fixed on the supporting disk by
epoxide resin adhesive. The supporting disk serves for rotating the
abrasive laminas and for the pressure necessary for the grinding
job to be transmitted by the operator from the driving motor to the
abrasive laminas and, consequently, to the subject that is to be
machined. Consequently, the supporting disk is only of indirect
importance for the result of the grinding job. Another important
function of the supporting disk resides in ensuring the necessary
safeguard against centrifugal fracture of the surface grinding
wheel. Surface grinding wheels are regularly operated at a
circumferential speed ranging from 50 m/s to 80 m/s. The
considerable mechanical stresses that occur in the supporting disk
in this case demand for the use of high-strength material.
[0005] It is known from DE 200 05 548 U1 and DE 299 14 325 U1 to
make the supporting disk of metal.
[0006] DE 298 05 508 U1 further teaches to manufacture a supporting
disk for a surface grinding wheel from metal and to provide the
outer edge thereof with a plastic material protective
arrangement.
[0007] It is known from DE 299 10 931 U1 to manufacture a
supporting disk for a surface grinding wheel from synthetic resin
which is at least partially reinforced by natural fibers.
[0008] It is further known to embody supporting disks as
glass-fiber reinforced phenolic resin bodies. The production costs
are very high in particular when a supporting disk of this type
includes a plurality of textile-glass fabrics. More than five and
even more than twelve layers of textile-glass fabrics are used as a
safeguard against centrifugal fracture.
[0009] In particular the flexural strength of the supporting disks
is of decisive importance as a safeguard of the tools against
centrifugal fracture. When loaded by centrifugal forces, the
supporting disk sags as a result of the weight of the abrasive
laminas that bears on it, which strongly loads the adhesive
mechanically, terminating in the laminas being torn off.
[0010] In order to obtain the required flexural strength of the
supporting disk, a sufficiently great number of glass fabrics must
be selected, which is the present level of knowledge. The necessary
number of fabric layers depends on the total weight of the abrasive
laminas that are mounted on the supporting disk. The number of
abrasive laminas is also directly proportional to the lifetime of
the tool. Therefore, tools that have a long lifetime must
com-comprise a plurality of fabric layers, for example twelve
layers, so as to comply with safety requirements.
SUMMARY OF THE INVENTION
[0011] It is an object of the invention to embody a supporting disk
for a surface grinding wheel in such a way that the supporting disk
can be manufactured at a low cost while keeping its highly
protective properties of safeguard against centrifugal fracture and
to embody a surface grinding wheel that comprises a supporting disk
of this type.
[0012] This object is attained in a supporting disk for a surface
grinding wheel, comprising a glass-fiber reinforced phenolic resin
body, which includes an upper covering layer of a textile glass
fabric or a glass-yarn layer; an intermediate layer of a fiber mat;
and a lower covering layer of a textile glass fabric or a
glass-yarn layer. According to the invention, a comparatively
expensive textile glass fabric or glass-yarn layer is utilized only
in the upper and lower covering layer, whereas a simple
intermediate layer in the form of a fiber mat is used as a filler
between these two covering layers. When the supporting disk is
loaded during grinding operation, mechanical stresses occur in
addition to the strain due to centrifugal force as a result of the
supporting disk sagging in the direction of its axis. The greatest
bending stresses occur upon loading of the surface areas, while the
intermediate area remains almost stress-free when loaded by
bending. The coverings of textile glass fabric or glass-yarn layers
have a higher loading capacity than the fiber-mat intermediate
layer. As opposed to the prior art number of five layers or more,
the supporting disk according to the invention only comprises three
layers, of which only the two exterior coverings consist of
comparatively costly fabrics or layers while the intermediate layer
consists of a comparatively low-cost fiber mat as a filler. The job
of the intermediate layer primarily resides in producing as great a
distance as possible between the two coverings that possess by far
greater tensile strength than the intermediate layer. As a rule,
the intermediate layer is thicker than the covering layers.
[0013] Generally, the design of the surface grinding disk that is
manufactured using a supporting disk of this type is
conventional.
[0014] Further advantages, features and details of the invention
will become apparent from the ensuing description of exemplary
embodiments, taken in conjunction with the drawing.
BRIEF DESCRIPTION OF THE DRAWING
[0015] FIG. 1 is a central cross-sectional view of a surface
grinding wheel;
[0016] FIG. 2 is a plan view of a textile glass fabric;
[0017] FIG. 3 is a plan view of a glass-yarn layer;
[0018] FIG. 4 is an explosive view of a blank for a supporting disk
with covering layers of textile glass fabric; and
[0019] FIG. 5 is an explosive view of the blank for a supporting
disk with glass-yarn-layer coverings.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0020] As seen in FIG. 1, the fundamental and familiar design of a
surface grinding wheel includes a supporting disk 1 and abrasive
laminas 2. The supporting disk 1 has the shape of a circular ring
with a central longitudinal axis 3. Concentrically of the axis 3,
it is provided with an opening 4 for accommodation of the driving
shaft of a driving motor. The supporting disk 1 further comprises
an outer annular marginal area 5, to which the abrasive laminas 2
are customarily fixed by means of glue (not shown), overlapping
each other. As further seen in FIG. 1, the supporting disk again
comprises an upper covering layer 6, an intermediate layer 7 and a
lower covering layer 8.
[0021] The upper covering layer 6 and the lower covering layer 8
either consist of a textile glass fabric 9 as seen in FIG. 2, or of
a glass-yarn layer 10 as seen in FIG. 3. The textile glass fabric 9
as well as the glass-yarn layer 10 consist of parallel warp threads
11 and equally parallel weft threads 12 which are perpendicular to
the warp threads 11. As illustrated in FIG. 2, the difference
resides in that, in the case of the textile glass fabric 9, the
weft threads 12 are led alternately above and below the neighboring
warp threads 11 for the linen weave illustrated. Of course, it is
conceivable to make use of a weave other than the linen weave.
Fundamentally, the fabrics 9 include two systems of warp threads 11
and weft threads 12 that cross at right angles for a given type of
weave. As opposed to this, in the case of the glass-yarn layer 10,
the warp threads 11 lie on a plane and the weft threads 12 also are
on a plane on top of the warp threads 11. In this case too, the
warp threads 11 on the one hand and the weft threads 12 on the
other are close side by side as seen in FIG. 3.
[0022] The warp threads 11 and the weft threads 12 may be glass
fibers preprocessed into yarns or twines. For cost reasons, they
will however be rovings serving the purpose. Fundamentally, rovings
constitute a plurality of textile glass filaments that are combined
nearly in parallel, having among them a given, largely identical
strand fineness.
[0023] The intermediate layer 7 consists of a fiber mat, the term
fiber mat also implying a fiber fleece or a fabric of a volume
enlarged by needling. The needling of fabrics, known in the art,
serves to multiply, for example to triplicate, the volume, i.e. the
thickness, thereof, whereas the tensile strength is reduced by 50
percent, which is however of no importance--as explained at the
outset. Natural fibers, for example hemp or sisal, may be used as a
fiber material as well as synthetic organic fibers such as
polyester or polypropylene or textile glass fibers.
[0024] FIG. 4 is an explosive view of a blank 15 for the upper
covering layer 6, a blank 16 for the intermediate layer 7 and a
blank 17 for the lower covering layer 8. All the blanks 15 to 17
already have the opening 4, but they are still plane. In FIG. 4, a
textile glass fabric 9 is used for the upper covering layer 6 and
the lower covering layer 8. Fundamentally, there are the following
four possibilities of combination of the upper covering layer 6 and
the lower covering layer 8:
1 upper covering layer 6 lower covering layer 8 textile glass
fabric 9 textile glass fabric 9 textile glass fabric 9 glass-yarn
layer 10 glass-yarn layer 10 glass-yarn layer 10 glass-yarn layer
10 textile glass fabric 9
[0025] FIG. 5 is an explosive view of the blank 15 and the blank 17
of glass-yarn layers 10.
[0026] Producing a supporting disk 1 takes place as follows:
[0027] The textile glass fabrics 9, glass-yarn layers 10 and the
fiber mats 14 are produced and combined in such a way that a
textile glass fabric 9 or a glass-yarn layer 10 as an upper
covering layer 6 and as a lower covering layer 8 accommodate the
intermediate layer 7 between them. The three combined layers 6 to 8
may be sewn together by threads as a safeguard during transport.
This compound of layers or the individual layers are impregnated by
phenolic resin, from which the blanks are subsequently punched.
[0028] This package of the upper covering layer 6, intermediate
layer 7 and lower covering layer 8 is pressed and cured under the
action of pressure and heat for the glass-fiber reinforced phenolic
resin supporting disk 1 to form, which is then customarily worked
into a surface grinding wheel.
* * * * *